Pfizer states that there is minimal evidence that demonstrates that people using "statins" are at risk for cognitive impairment. Spontaneous reports of memory changes associated with any cholesterol-lowering treatment are rare, and only provide a possible signal of adverse events occurring in the community. While more study may be required, it is important to note that a causal relationship between Atorvastatin (Lipitor), Simvastatin (Zocor, Lipex, Simvar), Pravastatin (Pravachol) and Fluvastatin (Lescol) and cases of memory changes has not been established.